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Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A chemically defined liquid medium has been developed for the study of the physiology and antigen production of the Legionnaires disease bacterium. The medium contains basal salts, vitamins, alpha-ketoglutaric acid, pyruvate, 0.05% l-cysteine, 0.05% glutathione, and a mixture of 20 additional amino acids, each of 0.01% final concentration, except serine, which was at 0.1%. The medium in shake culture at 37 degrees C with increased CO2 at pH 6.5, supports the maximum rate of growth, the highest cell yields, and the maximum cell surface antigen as distinguished by specific fluorescein isothiocyanate-conjugated antibody. Studies during the development of this medium showed that CO2, pyruvate, and alpha-ketoglutarate strongly stimulated growth; that cysteine and methionine were required for growth; and that serine, threonine, histidine, tyrosine, and tryptophane were energy sources. Glutathione substituted for cysteine, but cystine did not. The organisms did not use glucose and polysaccharides, as judged by cell yields when these carbohydrates were present or absent. The chelators malate, citrate, and ethylenediaminetetraacetic acid totally inhibited growth. Beta-mercaptoethanol, thioglycolate, dithiothreitol, and Tween 80 (0.05%) inhibited growth strongly or completely. Catalase activity was extremely weak or absent. Morphology varied, depending upon conditions and phases of growth. In general, filamentous forms became chains of cigar-shaped bacilli fragmenting to pairs and becoming coccoidal in the late stationary pha-e of growth. The organism grew at 25, 30, and 37 degrees C. Although they varied in their growth characteristics, 10 isolates were passed for five transfers in the chemically defined broth, giving maximum rates of growth, cell yields, and antigen production.
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PMID:Development of a chemically defined liquid medium for growth of Legionella pneumophila. 3 86

A chemically defined medium containing 21 amino acids and inorganic salts was developed which supported the growth of four isolates of Legionnaires disease bacterium (Legionella pneumophila). Growth in liquid defined medium at 37 degrees C with shaking approximated the generation time and growth kinetics observed for growth in complex media. After a 3-h lag, the culture grew exponentially with a generation time of 6 h and reached a maximum optical density of 230 Klett units (170 Klett units corrected for pigment). A soluble brown pigment was first observed as the culture entered late exponential to early stationary phase of growth. Morphologically, L. pneumophila grew in the liquid defined medium with extensive filamentation and numerous intracellular lipid granuoles. L-Serine, L-methionine, and L-cysteine were required for optimum growth. The latter amino acid could be replaced by L-cystine or reduced glutathione but not by D-cysteine, thiomalate, thioglycollate, or 2-mercaptoethanol. Ferric iron was needed for maximum growth, but supplemental iron was not an essential growth requirement. Carbohydrates (i.e., glucose) or organic acids did not stimulate growth. In fact, pyruvate, acetate, and citrate all gave varying degrees of inhibition (69, 37, and 0% of control growth, respectively).
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PMID:Growth of Legionnaires disease bacterium (Legionella pneumophila) in chemically defined medium. 50 Jul 95

Two strains of Legionella pneumophila serogroup 1 monoclonal subgroup Pontiac were grown for the first time in continuous culture using a chemically defined medium. The influence of temperature on physiology and morphology was investigated by fixing the growth rate (equal to the dilution rate, D) at 0.08 h-1 and controlling the pH and dissolved oxygen concentration of the culture. Serine provided the principal source of carbon and energy but growth was limited by tyrosine. The bacterium behaved as a microaerophile in this medium, with maximal growth occurring at 0.31 (mg O2)I-1 (equivalent to a dissolved oxygen tension of 4% (v/v) air saturation at 30 degrees C). The cultures consisted of flagellated, short rods at 24 degrees C, but exhibited an increased level of pleomorphism and the loss of flagella as the temperature was increased to 37 degrees C. The presence of intracellular granules was noted, and their abundance was temperature-dependent. Polyhydroxybutyrate was present in L. pneumophila, and the proportion of the cell dry weight that it accounted for varied with temperature, being maximal at 24 degrees C. The ratio of saturated to unsaturated fatty acids in the cells decreased as the temperature was reduced towards 24 degrees C, so as to maintain membrane fluidity at low growth temperature.
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PMID:Physiology and morphology of Legionella pneumophila in continuous culture at low oxygen concentration. 147 56

Antitryptic activity of human blood serum was decreased after incubation with metalloproteinase from Legionella pneumophila. The enzymatic activity depends on the time of incubation as well as on the ratio between the enzyme content and blood serum total protein. Cross immunoelectrophoresis, involving monospecific rabbit antiserum towards the alpha 1-antitrypsin, demonstrated highly effective hydrolysis of alpha 1-antitrypsin by the metalloproteinase. As shown by polyacrylamide gel electrophoresis the metalloproteinase hydrolyzed acid stable inhibitor of serine proteinases into fragments with distinct loss of the inhibitor activity. Thermolysine hydrolyzed similarly the proteins studied but at a lower rate. The metalloproteinase from L. pneumophila appears to be mainly responsible for production of utilizable components from protein substrates involved in vital activity of the bacteria. It may not be excluded that the enzyme is able to impair some host protective mechanisms.
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PMID:[The effect of Legionella pneumophila metalloproteinase on certain human blood proteins. Cleavage of anti(1)-antitrypsin and acid-stable serine proteinase inhibitors]. 194 72

p-Nitroanilides of antranyloyltripeptides of the general structure Abz-Ala-Ala-P'1-pNA (P'1 = Phe, Leu, Ile, Val) containing intramolecularly quenched fluorescent groups (Abz is a fluorogenic group and pNA is a quencher of fluorescence) were prepared by combination of chemical and enzymatic methods. Thermolysin and metalloproteinases from Legionella pneumophila and Thermoactinomyces species were shown to hydrolyse Ala-P'1 bond of the peptides with simultaneous 4-7 fold increase in fluorescence. Kinetic parameters for enzymatic hydrolysis of the substrates were determined. Metalloendopeptidases can be assayed in the presence of serine proteinases (of the subtilisin type) using Abz-Ala-Ala-Ile-pNA or Abz-Ala-Ala-Val-pNA.
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PMID:[New fluorescent substrates for metalloendopeptidases with internal quenching of fluorescence]. 342 2

Phenylalanineaminopeptidase was isolated and purified from the culture filtrate of Legionella pneumophila by affinity chromatography on O-tert-butyl-L-threonyl-L-phenylalanyl-L-prolylglycyl-aminosilo chrom and by gel-filtration; a 401-fold purification with a yield of 18% was achieved. The enzyme was a metalloenzyme with a molecular weight of 35000 and a pI of 5.8. It was stable at pH 7-9 and had an activity optimum in the range of pH 8-9.5 with L-phenylalanine p-nitroanilide as substrate. Enzyme activity was highest towards the latter compound, substantially lower towards L-leucine p-nitroanilide and only marginal towards other p-nitroanilides. Besides phenylalanineaminopeptidase, a metalloproteinase and a serine proteinase were also detected in L. pneumophila culture filtrate.
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PMID:Proteinases of Legionella: phenylalanineaminopeptidase of L. pneumophila. 371 61

The amino acids L-arginine, L-isoleucine, L-leucine, L-methionine, L-serine, L-threonine, and L-valine were essential for the growth of Legionella pneumophila in a chemically defined medium. A partial requirement for L-cysteine (or L-cystine) was also observed. A minimal medium containing only the eight required amino acids supported the growth of this bacterium only if the medium was supplemented with L-glutamic acid. This latter compound was the only amino acid capable of stimulating growth in the eight-amino acid medium.
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PMID:Amino acid requirements for Legionella pneumophila growth. 611 50

The utilization of amino acids and other compounds as carbon and energy sources by Legionella pneumophila was examined. Based on the stimulation of oxygen consumption in washed-cell suspensions, glutamate, serine, threonine, and tyrosine were the only amino acids which were utilized as energy sources. Other stimulators of oxygen uptake were lactate, pyruvate, acetate, fumarate, and succinate. Citrate was a good stimulator only when the bacteria were grown in the presence of the substrate. Radiolabeling studies showed that [14C]glutamate was rapidly metabolized, with the label distributed evenly in all cell fractions. [14C]pyruvate and [14C]acetate were incorporated into the lipid-containing cell fraction, whereas glucose and glycerol were found in both the lipid- and polysaccharide-containing cell fractions. Radiorespirometry of differentially labeled [14C]glucose indicated that this compound was metabolized primarily by the pentose phosphate and Entner-Doudoroff pathways rather than by the glycolytic pathway.
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PMID:Intermediary metabolism in Legionella pneumophila: utilization of amino acids and other compounds as energy sources. 613 45

The objective of this study was to evaluate by relatively simple metabolic tests the usefulness of buffers and energy sources commonly used in Legionella growth media. Legionella pneumophila serogroups 1 to 6, Legionella micdadei, and Legionella bozemanii were grown in an enriched charcoal-yeast extract diphasic medium. The cells were washed thrice, suspended in various buffers (pH 6.9) with 1 or 5 mM MgSO4, and used immediately or after controlled-rate cryopreservation. CO2 produced and C incorporated into the cold trichloracetic acid-insoluble fractions from 14C-labeled substrates were determine. Potassium phosphate buffer (0.02 M) was as satisfactory as organic buffers for glutamate metabolism, but the addition of KCl or NaCl reduced activity. Metabolic activity for glutamate was not lost upon cryopreservation, and cryopreserved cells were used to test the utilization of other single or paired substrates. Rates of activity for serine, glutamate, threonine, and pyruvate, in this descending order, were high, and those for alpha-ketoglutarate, succinate, and gamma-aminobutyrate were low. Although glutamine was not used as rapidly as glutamate, when added to glutamate it was preferentially metabolized, possibly because of more rapid transport. When glutamate and serine were combined, glutamate furnished more C for CO2 and less for incorporation, whereas the reverse was true of serine. In conclusion, glutamate as an energy source may in some cases spare other amino acids for synthesis. alpha-Ketoglutarate, a common constituent of Legionella media, may reduce oxygen toxicity but is probably not a chief energy source.
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PMID:Substrate utilization by Legionella cells after cryopreservation in phosphate buffer. 614 14

The amino acids required for growth and as energy sources by 10 strains of Legionella pneumophila were determined by using a chemically defined medium. All strains required arginine, cysteine, isoleucine, leucine, threonine, valine, methionine, and phenylalanine or tyrosine. Most strains (7 of 10) required serine, and two strains had to be supplied proline before growth could be established. All 10 strains used serine and, to a lesser extent, threonine as the sole sources of carbon and energy. The Y serine calculated was 94.9 +/- 8.5 g (dry weight) of cells/mol of serine. Assuming that the value of Y adenosine 5'-triphosphate is 10.5, these results indicate that oxidative catabolism of 1 mol of serine yielded approximately 9 mol of adenosine 5'-triphosphate. This high yield suggests that although serine was the major source of carbon, other amino acids may also be metabolized.
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PMID:Amino acid requirements of Legionella pneumophila. 676 47


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